Two channel amps with clean and high gain

[OldHouseScott]

Howdy folks, here are two designs for two-channel, channel-switching amps. In both instances the high-gain side is based on the SLO/Recto dirty channel. Overall design is inspired by Carvin Vintage series and Legacy.

The first one I call the SLOVox and is a design I built into a gutted Carvin Belair chassis. I then mounted it in a cabinet I got from Collins amplification. It looks a lot like a Budda cabinet -- very large for a single 12". I designed a turret board in the Hoffman style and had Ken at turretboards.com build it. The relays are 3VDC units from Carvin. 5VDC might work.

Schematic:

[OldHouseScott]

Layout:

[OldHouseScott]

The chassis still had the PCB for the EL-84 output tubes and associated circuitry (grid stoppers and screen resistors), so it didn't make it onto the turretboard.

Turretboard:

[OldHouseScott]

My original design was to do a Fender clean channel. I had already drawn it when I decided to go with the top-boost.

Schematic:

[OldHouseScott]

Sorry, no turretboard for this one.

Layout:

[LooseChange]

Nice!  I really like 2 channel amps. Built a few myself.
On the second design, do you find that the clean channel is much louder than the dirty channel?
How did you generate the relay power supply?

[OldHouseScott]

Both seem to be fairly loud, I can't say I noticed the clean channel being particularly louder than the dirty channel.

If you look at the far right end of the SLOVox layout, you'll see two 100ohm resistors, two diodes and a large cap. I connected the heater voltage to the junctions of the resistors and diodes to make a full-wave rectifier for the DC for the relays.  The bottom rail gets grounded. I "borrowed" that idea from Carvin as well.

[navdave]

How does the anode follower sound with all that gain behind it on your overdrive channel?

[spankenstrat]

Scott, Check your PM!  ;)

[OldHouseScott]

Navdave, sorry for not replying sooner. I don't often check this part of the site. As to your question, I think it sounds very good. It's a tad brighter than my Rectoverb (very similar overdrive channels). I've never heard a SLO in person so I can't compare the two. Obviously if you crank the gain past 2 or 3 o'clock it's way over the top. Heavy crunch to thick distortion can be found between 9 o'clock and noon. It doesn't really do light crunch too well.

spankenstrat, PM coming your way.

[navdave]

Wow sounds like its a monster did you ever put up any sound clips of the amp switching from clean to overdrive?

[OldHouseScott]

Put a clip in the Video-Audio section. Sorry, moved to the Sound Bits section.

[navdave]

With that many gain stages on the overdrive channel is a gain make up stage needed even with the tone stack
hung off of the anode?